6 Acknowledgments 87 7 References 88 Subject Index 95 VIII Abbreviations A cerebral aqueduct anterior deep dorsal nucleus, CGM AD AP anterior pretectal nucleus AR auditory radiation ASD anterior superficial dorsal nucleus, CGM BA brachium, accessory (medial) nucleus, IC BIC brachium of inferior colliculus BSC brachium of superior colliculus cerebellum CB CC caudal cortex, IC CF cuneate fasciculus CG central gray CGL lateral geniculate body medial geniculate body CGM commissure of inferior colliculus CIC CIN central intralaminar nucleus CL lateral part of commissural nucleus, IC CM central medial nucleus CN central nucleus, IC CORD spinal cord CP cerebral peduncle CSC commissure, SC CUN cuneiform area, IC D dorsal nucleus, CGM DA anterior dorsal nucleus, CGM DC dorsal cortex, IC DD deep dorsal nucleus, CGM DI dorsal intercollicular area DM dorsomedial nucleus, IC DMCP decussation of superior cerebellar peduncle DS superficial dorsal nucleus, CGM EYE enucleation FX fornix GN gracile nucleus HIT habenulo-interpeduncular tract inferior colliculus IC III oculomotor nerve IN interpeduncular nucleus L posterior limitans nucleus LC laterocaudal nucleus, IC LI lateral intercollicular area LL lateral lemniscus lateral mesencephalic nucleus LMN LN lateral nucleus, IC LP lateral posterior nucleus LPc caudal part of lateral posterior nucleus LV pars lateralis, ventral nucleus, CGM M medial division, CGM MB mammillary bodies middle cerebellar peduncle MCP MES V mesencephalic nucleus of trigeminal tract MI medial intercollicular area ML medial lemniscus MLF medial longitudinal fasciculus MT mammillothalamic tract MZ marginal zone, CGM OC oculomotor nuclei occipital cortex lesion OCC OT optic tract

In birds, the beak is the most important organ for manipulative actions: its manipulative capabilities vary as much as those of the forepaws and snouts of mammals. For the peripheral parts and at brainstem levels, the sensorimotor circuit of the avian oral region is roughly similar to the mammalian, but is strikingly different at higher levels of the central nervous system (CNS) (Ariens- Kappers et al. 1936). Our field of interest is the organization of the telencephalic areas involved in the manipulative actions of the bill. The goose was chosen as a subject because of the extensive development of the tactile system of the oral region. The mechanoreceptors in the lower and upper beak are innervated by the trigeminal nerve (Cords 1904; Berkhoudt 1980), while the tongue is innervated by branches of the glossopharyngeal and hypoglossal nerves (Cords 1904). In the ganglion semilunare, the perikarya of the fibers of the trigeminal nerve are separated into a distinct ophthalmic population, and two mutually overlap- ping maxillary and mandibulary populations (Dubbeldam and Veenman 1978; Noden 1980). In duck and cockatoo both the glossopharyngeal nerve and trige- minal nerve relay in the metencephalic principal sensory nucleus of the trige- minal nerve (PrV) (Dubbeldam et al. 1979; Dubbeldam 1980; Wild 1981). In PrY the three trigeminal branches are represented in an overlapping dorsoventral sequence (Zeigler and Witkovsky 1968; Dubbeldam and Karten 1978).

Again rapid advances in the brain sciences have made it necessary, after only a few years, to issue a revised edition of this text. All the chapters have been reviewed and brought up to date, and some have been largely rewritten. The major revision has occurred in the chap ters on the autonomic nervous system and the integrative functions of the central nervous system. But in the discussion of the motor systems and other subjects as well, recent insights have necessitated certain conceptual modifications. In the description of the autonomic nervous system, the role of the intestinal innervation has been brought out more clearly than before. In addition, there is a new presentation of the physiology of smooth muscle fibers, and more attention has been paid to the postsynaptic adrenergic receptors, because of the increasing therapeutic signifi cance of the at f3 receptor concept. A substantial section on the genital reflexes in man and woman, including the extragenital changes during copulation, has also been added. The text on the integrative functions of the central nervous system has been expanded to include, for the first time, material on brain metabolism and blood flow and their dependence on the activity of the brain. Reference is also made to recent results of research on split brain and aphasic patients and on memory, as well as on the physiol ogy of sleeping and dreaming.

In the search for explanations for differences in the shape of skulls and their phylogenetic development, the morphology of the skull must be seen in connec tion with the functions it has to perform. The skull encloses the brain and the sense organs and provides them with physical protection. It also houses the initial parts of the respiratory and digestive systems and together with the jaws constitutes a tool capable of cutting and grinding food. The skull must be able to withstand forces imposed upon it by chewing, by movement of the head, by the weight of the head itself, and by impact loadings. An investigation of the factors influencing the shape of the skull has to take into account not only the above-mentioned functions. The shape also de pends on the phylogenetic history 9f the species concerned, which prescribes a basic bauplan and places restrictions on the extent to which functions can influence the design of structural units. The possibilities for variations in skull shape are also limited by ontogenetic development, since the shape of the adult skull is the result of intermediate stages of development, at each of which the skull was a functioning unit. Body size and absolute and relative size of the sense organs in the head also play an important role in determining the shape of the skull."

At the end of the nineteenth century, controversy arose as to precisely when the first glial cells originate during development of the central nervous system, and to date, the issue has not been satisfactorily resolved. His (1889, 1890) noted that, even in the earliest developmental stages of the germinallayer, there appeared to be two distinct cell types. The cells which he called Spongioblasten were thought to be glial precursors from which all mature glial cells derive; Keimzellen, in contrast, were regarded as forming 1 neurons. His was working on the assumption that the very first preneurons migrate into a preexisting framework of glial eelIs. In contrast to this view, Schaper (1897) regarded both Keimzellen and Spongioblasten as belonging to a common population of proliferating and pluripotent stem cells which begin differentiation into glial and neuronal cells at late developmental stages. It is this latter view which is the basis of the most recent studies on the subject (e. g. , Caley and Maxwell1968a, 1968b; DeVitry et al. 1980). The concept of one common stem cell seemed to be supported both by experiments using 3H-thymidine autoradiography (Fujita 1963, 1965b, 1966; Sauer and Walker 1959; Sidman et al. 1959) and by ultrastructural studies (Fu- jita 1966; Hinds and Ruffet 1971; Wechseler and Meller 1967) indicating that structural differences, which His presumably used to define his two cell types, could be related to different stages of the mitotic cycle.

The traditional education of the neurosurgeon and duce simultaneous contrast preparations of the ar- the clinician working in related specialties is based teries and veins and thus obtain a complex photo- on their presumed knowledge of the macroscopic graphic representation of the structures of the prep- anatomy of the brain as traditionally taught. Most aration. neurosurgical textbooks, therefore, provide macro- The manuscript and drawings were completed in the scopic views of sections of the operative site. The years 1974-1976 after almost two decades of neu- literature that has accumulated in recent years on rosurgical work. The data worked out in the early the subject of microneurosurgical operations also stages (Chapter 1 in particular) were used by the follows this principle. author as the basis for teaching programmes at the For some years, however, the customary macro- University of Giessen. Chapters 2-7, dealing with scopic representation of the anatomy of the brain the operative technical aspects, were produced after has been inadequate for the needs of the neurosur- mid-1975 and used by the author as the basis for geon using refined modern operative techniques. microneurosurgical teaching of his colleagues at the Furthermore, despite their detailed presentation, University of Freiburg. stereotactic atlases are also insufficient for neuro- My thanks are due to Doz. Dr. E.

The anterior inferior cerebellar artery (AI CA) is one of the major branches of the basilar artery and supplies part of the pons, the upper medulla, and the cerebellar hemisphere. The artery can be visualized by means of vertebral angiography. This technique of examination was carried out for the first time in 1933 by Moniz and co-workers (Moniz and Alves 1933, Moniz et al. 1933). During the decades that followed, angiographic techniques improved considera bly, with the result that more details of the angioarchitecture of the posterior cranial fossa could be demonstrated. Satisfactory visualization of the AICA and its branches depends greatly on the use of subtraction, and this is the reason why detailed reports on the angiographic appearance of the artery were for the greater part published after 1965, when subtraction techniques were more consistently used (Takahashi et al. 1968, 1974; Gerald et al. 1973). The angiographic appearance of the various segments of the AICA in the lateral projection, both in the normal situation and in the presence of tumors, has been studied by Naidich et al. (1976a, b). The primary aim was to recognize and denominate the separate branches, loops, and segments of the AICA in order to locate tumors on the basis of displacements of portions of the artery. The fact that the course, caliber, and distribution of the AICA are very variable was not emphasized."

During development two strongly interrelated processes can be discerned in the central nervous system (eNS), namely morphogenesis and histogenesis. Most neuroembryological studies deal with histogenetic features virtually with- out any morphological elucidation. It must be stressed, however, that histogen- etic investigations should be based upon a thorough knowledge of morphogene- sis. This holds especially for the forebrain, which during development is sub- jected to drastic transformations, particularly when only two-dimensional sec- tions are used. Therefore the present study on morphogenesis forms the first part of a research project on the ontogenesis of the brain in the rhesus monkey. The second part (Gribnau and Geijsberts 1984) will deal with the early histogene- sis of the forebrain. The first recognizable precursor of the eNS in vertebrates is the neural plate, which, after the formation of the germ layers, is induced in the ectoderm. The lateral margins of the neural plate start to rise, forming a neural groove. Eventu- ally, they meet dorsally in the midline and fuse, resulting in the formation of the neural tube. The ultimate sites of closure at either end of the neural tube are called the anterior and posterior neuropores. Before the closure of the anterior neuropore, which precedes that of the posterior neuropore, the anlage of the eNS can be divided into a narrow elongated caudal part, the future spinal cord, and a wider rostral part, the precursor of the brain.

3. 11 Stage XI (ca. 10. 5-12. 5 mm) 48 3. 11. 1 Axial Relations 48 3. 11. 2 Lateral Relations 49 3. 11. 3 Summary . . . . 52 3. 12 Stage XII (ca. 13-16 mm) 53 3. 12. 1 Axial Relations 53 3. 12. 2 Lateral Relations 56 3. 12. 3 Summary 59 4 Discussion . . . . . 60 4. 1 Introduction 60 4. 2 Early Differentiation of the Somite Mesoderm 60 4. 2. 1 Dermatome . . . . 60 4. 2. 2 Myotome . . . . . . . . . . 61 4. 2. 3 Somitic Mesenchyme . . . . . 61 4. 3 Development of the Axial Mesenchyme 63 4. 4 Development of the Somitic Mesenchyme 66 4. 4. 1 Segmentation Process in the Somitic Mesenchyme 66 4. 4. 2 Differentiation of the Somitic Mesenchyme into the Mesenchymatous Primordium of the Axial Skeleton 70 4. 4. 2. 1 Metameric Condensations: Arcual and Costal Processes 70 4. 4. 2. 2 Axial Somitic Mesenchyme (Transverse Commissure) 73 4. 4. 2. 3 Perichordal Tube . . . . . . . . . . . . . . 74 4. 4. 2. 4 Linkage Between Lateral and Axial Segmentation 78 4. 4. 2. 5 Origin of the Mesenchymal Vertebral Bodies . . . 81 4. 4. 2. 6 Blastema of Vertebral Processes and its Relationship with the Blastemic Vertebral Body . . . . . . . . . . . . 83 4. 4. 3 Differentiation of the Somitic Mesenchyme in Relation to the Development of the Peripheral Spinal Nervous System 85 4. 5 Differentiation into Cartilaginous Axial Skeleton . . . . . . 89 . 4. 6 Differentiation of Myotomes; Morphology of the Developing Myotome . . . . . . . . . . . . . . . . . . . . . . . . 92 4. 7 The Notochord . . . . . . . . . . . . . . . . . . . . . 94 Some Remarks on the "Neugliederung" Concept with Special At 4."

The testis is composed of seminiferous tubules and interstitial tissue. The most important component of the interstitial tissue are the testosterone-producing Leydig cells. The seminiferous tubules contain the successive generations of germ cells, which can only exist in the presence of Sertoli cells. Sertoli cells mediate the effect of testosterone, which is indispensable for the maintenance of spermatogenesis. Consequently, the function of the Sertoli cells depends large lyon the function of the Leydig cells, and a local control mechanism between the two cell systems has been assumed. Sertoli cells are supposed to interfere with the regulation of Leydig cell hormone production (Aoki and Fawcett 1978; Sharpe et al. 1981). Few cell types of the testis have received as much attention in recent years as have the Sertoli cells. While comprehensive data had accumulated concerning the differentiation of germ cells, there was formerly little information available on the influence of Sertoli cells on this process. Only through recently developed methods and experimental approaches could their central role in spermatogene sis be verified. Sertoli cells are the only somatic cells in the seminiferous tubules. Their origin is still disputed (for references see Ritzen et al. 1981). They supposedly stem either from the coelomic epithelium or from mesenchymal cells of the genital ridges. According to Wartenberg (1978) they are derived from a gonadal blas tema containing cells from both the coelomic epithelium and the mesonephros."

The Ornithopoda, one of five suborders within the Ornithischia, was originally proposed by Marsh in 1881 to include those bipedal dinosaurs possessing a predentary bone fitted over the rostral end of the mandibles. Ornithopods as recognized today can be further characterized by moderately long facial skele- tons equipped with well-developed, often toothless premaxillae and moderate to large external nares. Maxillary and dentary dentitions vary but usually consist of at least one replacement series beneath the functional set; some have many rows of successional teeth. Tooth morphology suggests ornithopods were suc- cessful herbivores but, as will be discussed, the precise way(s) in which ornitho- pods chewed their food, hence lending important information about their tro- phic position, has not been settled. Postcranially, ornithopods show specializa- tion for bipedality in hindlimb construction and lack well-developed protective structures on their flanks, back, and tail. The Ornithopoda can itself be divided into five families: Fabrosauridae, He- terodontosauridae, Hypsilophodontidae, 19uanodontidae, and Hadrosauridae (subdivided into the subfamilies Hadrosaurinae and Lambeosaurinae). Both fabrosaurids and heterodontosaurids, first known from the Late Triassic and Early Jurassic of Argentina and South Africa, were small animals differing in details of cranial, dental, and appendicular anatomy. Fabrosaurids are be- lieved to represent the basal ornithopod stock (Galton 1972, 1978; Thulborn 1970a, 1972). During the Jurassic, ornithopods underwent major radiations that included the medium- to large-sized Hypsilophodontidae and the large- bodied Iguanodontidae, both of which survived into the Cretaceous.

In 1953, at the grand age of 92, Ferdinand Hochstetter submitted his famous collection of photographs of human embryos entitled: "Uber die Entwicklung der Formverhaltnisse des menschlichen Antlitzes." Together with others papers, this contribution was published in 1955, a year after Hochstetter's death. In unbroken combativeness, Hochstetter discussed his results with regard to those of earlier embryologists and to those of his own lifetime. Thus, in an obituary, Elze (1956) reported about one of Hochstetter's letters from the year of his death (1954): "nur einige blodsinnige Behauptungen, die Fischel in seiner Ent- wicklung des Menschen verzapft hat, mochte ich vielleicht noch annageln," which may be translated as: "I would just like to pin down a few silly assertions that Fischel made in his Entwicklung des Menschen." In the first two paragraphs of his paper Hochstetter stated (in German, here translated freely): When I decided to write a detailed paper about the development of the morphology of the human face, too [in addition to a paper about morphology of the extremities in human embryos], I was especially moved by the fact that in none of the German manuals and textbooks on embryology known to me is there to be found a presentation of the development of the human face which could be considered - eveJ;l to a limited extent - rich in details, true, sufficiently illustrated, easy to understand by students as well as by scien-

Fish have adapted extremely successfully to the extremes of the aqueous environ ment, with the teleosts being outstanding in this respect. Amongst the class Pisces are pelagic species which must maintain certain swimming speeds in order to remain buoyant, species which migrate over thousands of miles, abyssal species living in waters with markedly reduced oxygen content, species living in the subzero waters of the Antarctic and also the obligatory air-breathing species of the tropics. Even in a comparatively benign environment such as the relatively shallow waters over continental shelves, the lifestyle of fish species varies greatly, with sedentary benthic and pelagic shoaling species coexisting within a comparatively narrow depth-range. Clearly, widely varying physiologi cal demands are made on species occupying such different environments and exhibiting such different lifestyles, and the successful provision of an adequate oxygen supply to the tissues is therefore of paramount importance to the fish. It follows that the demands made on the fish heart in irrigating the gill vascula ture will vary greatly according to the lifestyle and habitat of a particular species, and it is therefore surprising that authors reporting physiological, pharmacologi cal, biochemical and morphological investigations on the hearts of a consider able number of cyclostome, elasmobranch and teleost species imply that their results and conclusions can be extended to "the fish heart" in general."

1. 1 Brief History The diversity of cells constituting the central nervous system did not deceive last century neurohistologists in recognizing that this organ contained essentially two cell types: the nerve cells, or as termed according to the emerging concept of neural contiguity, the neurons, and the neuroglial cells. Neurons were clearly shown to be the means of excitability, impulse generation, impulse transmission, and connectivity in the neural tissue. The neuroglia, as indicated by its name (YAloc=cement or glue) given by Virchow (1860), was thought to be the cement ing material ensuring the coherence of the nervous tissue, filling in the spaces of the neuropil, and isolating neuronal cell bodies. While this supposedly passive role did not attract multidisciplinary research on the neuroglia, successful efforts were made to extend our knowledge of the physiology, morphology, and bio chemistry of neurons. As a result of this, the investigation of the neuroglia carried out in the first half of this century was mainly confined to morphology, often as a by-product of comprehensive analyses of neuronal systems. At any rate, the histological classification of the neuroglia was accomplished, laying a framework which has been used to the present day. Accordingly, the glia was divided into two major groups: the macro- and microglia. The former comprises two further subclasses, the astroglia and oligodendroglia."

Of all cytoarchitectonic structures in the brain of mammals, the hippocampus is perhaps the most conspicuous because of its unusual macroscopic and micro- scopic appearance. During phylogeny, the hippocampus has developed from a single cortical plate in amphibia into a complicated, three-dimensional convo- luted structure in mammals. Because of its clear lamination into axonal, perikaryal, and dendritic layers, the hippocampus has often been considered a simple cortex model. Indeed, this trilaminated construction resembles perhaps the least complicated type of neuronal cortex. There is a large literature describing hippocampal morphology in many species with respect to cytoarchitectonics, fiberarchitectonics, angioar- chitectonics, chemoarchitectonics, synaptology, and fine structure. On the other hand, up to the present day there has been no generally accepted concept on the main functions of the hippocampus, although many studies dealing with its physiological and biochemical properties and its possible influences on behav- ior have provided some valuable indications. Early investigators described the hippocampus as being a part of the "rhinen- cephalon" (e. g. Zuckerkandl 1887), together with other allocortical structures, such as the olfactory bulb, olfactory tubercle, and piriform lobe. Thus, the hippocampus was assigned to the olfactory system, and it was not until improved degeneration techniques were applied that this error could be corrected. It be- came clear that only part of the allocortical areas receive direct olfactory inputs, namely the retrobulbar region (anterior olfactory nucleus), precommissural hip- pocampus, olfactory tubercle, prepiriform region, periamygdalar region, and part of the entorhinal region.

In the operation of reasoning, the mind does nothing but run over its objects, as they are supposed to stand in reality, without adding any thing to them or diminishing any thing from them. If I examine the Ptolomaic and Copernican systems, I endeavour only, by my inquiries, to know the real situation of the planets; that is, in other words, I endeavour to give them, in my conception, the same relation that they bear towards each other in the heavens. To this operation of the mind, therefore, there seems to be always a real, though often unknown standard, in the nature of things; nor is truth or falsehood variable by the various apprehensions of mankind. D. Hume, The sceptic. In: Essays. Moral Political and Literary. Oxford University Press, Oxford, 1963, p. 166. Contents 1 Introduction 1 2 Materials and Methods 2 3 Observations . . . . 4 3. 1 Topography of the Medial Geniculate Body 4 3. 2 Cytoarchitectonic Subdivisions of the Medial Geniculate Body 4 3. 3 Neuronal Architecture of the Ventral Division 7 3. 4 Structure ofAxons in the Ventral Division 21 3. 5 Cortical Connections of the Ventral Division 27 3. 6 Neuronal Architecture of the Dorsal Division 27 3. 7 Structure of Axons in the Dorsal Nuclei 39 3. 8 Neuronal and Axonal Architecture of the Suprageniculate Nucleus and the Posterior Limitans Nucleus . . . . . . 43 3. 9 Cortical Connections of the Dorsal Division . . . . . . 49 3. 10 Neuronal and Axonal Architecture of the Medial Division 56 4 Discussion . . . . . . . . . . . . . . . . . . .

The result of more than two decades of research and practice, The Endless Web presents in clear, readable language a comprehensive guide to understanding and working effectively with the myofascial system, the "packing material" of the body. Myofascia is a flexible network of tissue that surrounds, cushions, and supports muscles, bones, and organs. It also acts as a riverbed containing the flow of interstitial fluid, and is a critical influence on the immune and hormonal systems. In daily life, this connective tissue is an underlying determinant of movement quality, mood, alertness, and general well-being. The Endless Web is a fully illustrated guide to understanding how myofascia works, its supportive role within the body's anatomy, and how gentle manipulation of the myofascial tissue is central to lasting therapeutic intervention and how it can be integrated into any bodywork practice.

Ever since the behavioral work of Lissrnann (1958), who showed that the weak electric discharges of some families of fish (hitherto considered useless for prey capture or for scaring away enemies) are part of a strange sensory system, these fish have attracted attention from biologists. The subsequent discovery of the electroreceptors in the skin of gymnotids and mormyrids (Bullock et al. 1961; Fessard and Szabo 1961) and the evidence that the ampullae of Lorenzini of nonelectric sharks and rays are also electro- receptors (Digkgraaf and Kalmijn 1962) was a start for a lively branch of physiological, anatomical, and behavioral research. Many fmdings of general importance for these fields have made the case to which extremes the performance of the central and peri- pheral nervous systems can be driven. Among those fmdings is the temporal accuracy of the pacemaker of some high-frequency fish which controls the electric organ, pro- bably the most accurate biological clock (coefficient of variation < 0. 0 1 %, Bullock 1982). The functional analysis of the pacemaker cells and their axons has established most of our knowledge on electrotonic synapses, the alternative to chemical synapses (Bennett et al. 1967), and of the implications of axonal delay lines for achieving extreme synchrony of parallel inputs to postsynaptic elements (Bennett 1972; Bruns 1971).

This monograph has attempted to bring together morphological and physiological studies of reptilian lungs, to analyze the nature of the resulting correlations, and to risk some speculations regarding the evolution of reptilian lung structure. Central to this work is the morphometric evaluation of the lungs in two species of lizard: "the teju (Tupinambis nigropunctatus Spix) and the savanna monitor (Varanus exanthema- ticus [Bosc]) which is presented here for the first time. These two species are similar in body form, and both are diurnally active predators, but their lungs are of basic- ally different structural types. The teju possesses relatively small, single-chambered (unicameral) lungs in which the homeycomb-like (faveolar) parenchyma is more or less evenly distributed along their length. In the monitor the lungs are large and many-chambered (multicameral), the individual chambers connecting to an unbranched, intrapulmonary bronchus. The parenchyma is in the form of shallow cubicles (ediculae), which are elaborated on the intercameral septa. The parenchyma is heterogeneously distributed within the lungs, tending to be most concentrated near the intrapulmonary bronchus and the middle third of the lung length. The ventral and caudal portions of these lungs are thin-walled and highly flexible. In both species those portions of the lungs which are most exposed to air convection possess dense capillary nets which almost completely cover both sides of the parenchymal partitions. In more distal regions of the parenchy- ma or of the lung, the intercapillary spaces become larger, creating a pseudo-single capillary net.

The study of the development of the spinal cord has a relatively long history. The spinal cord was singled out as a favorable site when cytological techniques were first applied to the study of the embryonic development of the nervous system. Bidder and Kupffer (1857), using the new procedure of hardening nerve tissue with chromic acid (Hannover 1844), made an investigation of spinal cord development in fetal sheep. They reported that the cellular central mass of the spinal cord develops before its fibrous envelope, deducing from this that the fibers of the white matter of the embryonic spinal cord were outgrowths of cells in the gray matter. Bidder and Kupffer also noted that in the spinal ganglia fibers grew out from cells in both directions, peripherally and centrally. Their report was one of the earliest ontogenetic lines of evidence in support of the later-formulated neuron doctrine (Waldeyer 1891). The spinal cord re mained a favorite topic of morphogenetic studies of the nervous system through out the last quarter of the nineteenth century, with seminal contributions made by His (1886, 1889), von Lenhossek (1889), Retzius (1898), and Ramon y Cajal (1960). Indeed, the preoccupation with the spinal cord in the early investigations of neural development had a lasting, and to some extent regrettable, influence on ideas about the ontogeny of the brain and on the terminology adopted by anatomists."

This full-color atlas is packaged with every new copy of the text, and includes 107 bone and 47 cadaver photographs with easy-to-read labels. This edition of the atlas contains a comprehensive histology photomicrograph section featuring over 50 slides of basic tissue and organ systems. Featuring photos taken by renowned biomedical photographer Ralph Hutchings, this high-quality photographic atlas makes an excellent resource for the classroom and laboratory, and is referenced in appropriate figure legends throughout the text.

Primary cortical areas receive a defmed input which makes them especially appropria- te for investigating cortical functions. The striate area is the only isocortical field which can be delineated unequivocally in the human brain. Nevertheless, there have been only a few morphological studies of this particular area (cytoarchitectonic studies: Bailey and Von Bonin 1951, Beck 1934, Von Economo and Koskinas 1925, Filimo- noff 1932; myeloarchitectonic studies: Sanides and Vitzthum 1965, Vogt and Vogt 1919; pigmentoarchitectonic studies: Braak H 1976, 1977). For Golgi impregnations, Ramon y Cajal (1900, 1909-1911), Conel (1939-1967), and Shkol'nik-Yarros (1971) preferred the incompletely myelinated material taken from brains of young childre- a fact that somewhat restricts their descriptions of the human striate area. Pigment preparations (Braak H 1978) provide a detailed view of the lamination of cortical areas. Furthermore, many types of cortical nerve cells reveal a typicallipofus- cin-pigment pattern (Braak H 1974a). Thus, a correlation can be drawn between the type of neuron as classified in Golgi preparations and the characteristic number and distribution of lipofuscin granules found in the cell body. Neurolipofuscin granules can therefore be considered the internal markers. In this study several cell types of the striate area have been identified under light and electron microscopes by means of their characteristic pigmentation.

In many aspects hematopoiesis in newborn rodents, especially in rats, resembles hema- topoiesis in the human fetus in the 6th-7th month of gestation. In man the transition from the stage of liver to bone marrow erythropoiesis takes place at this time (Bessis, 1973). In rodents, however, the liver is almost the only place where hematopoiesis occurs until birth. Thereafter it is replaced to a growing extent by the bone marrow, which so far consists mainly of immature mesenchymal cells (Maximow, 1910; Cuda, 1970). Thus hematopoietic precursor cells appear in the sternum only around 30 h after birth. Just as in premature human infants, a macrocytic anemia can be demonstrat- ed in normal neonatal rats (Lucarelli et aI., 1964, 1968). Beside liver (fetal) and bone marrow, the spleen is involved in hematopoiesis. In rodents like rats and mice, splenic hematopoiesis persists more or less markedly until adulthood; in man, however, it ceases after birth and reappears only under certain pathological conditions (Fischer et aI., 1970; Hennekeuser et aI., 1967; Fresen, 1960).

The octapeptide angiotensin II (ANG II, Fig. 1) is the key effector substance of the renin-angiotensin system (RAS) (Werning 1972, Page and Bumpus 1974, Hierholzer 1977, Vecsei et al. 1978, Johnson and Anderson 1980 lit. ). ANG II is formed in two enzymatic steps. Renin acts on renin substrate, a glycoprotein, to produce angiotensin I (ANG I, a decapeptide), which in turn is acted upon by converting enzyme to form ANG II (Skeggs et al. 1968, Fig. 1). Renin substrate (angiotensinogen) is produced mainly in the liver (Page et al. 1941) and is a constituent of the ~-globulin fraction in the circulating plasma (Plentl et al. 1943). The two enzymes involved in the formation of ANG II from renin substra- te are formed at various sites in the body. Renin (E. C. 3. 4. 99. 19) is produced mainly in the granular epithelioid cells of the kidney (Cook 1971, Taugner et al. 1979, Davi- doff and Schiebler 1981), and converting enzyme (CE, E. C. 3. 4. 15. 1) occurs chiefly in the lung (Ng and Vane 1967, Bakhle 1974 lit. ) as well as in numerous other tissues, such as the juxtaglomerular apparatus of the kidney (Granger et al. 1969, 1972) and the brush border of the renal proximal tubule (Ward et al. 1975, 1976; Ward und Erdos 1977). The biological effects of ANG II are numerous.

The aim of this investigation is threefold: (a) to determine the time of origin of neurons of the rat cranial nerve ganglia; (b) to reexamine the embryonic development of the cranial nerve ganglia in the light ofthese dating results; and (c) to attempt to relate the chronology of these peripheral events to developmental events in those nuclei of the medulla that are intimately associated with the cranial nerve ganglia. Although thymidine-radiography has been used for over 2 decades to investigate the time of origin of neurons, most of these studies dealt with central nervous struc tures. There are relatively few studies available concerning the birth dates of neurons in the peripheral nervous system. In fact, to our knowledge, there is only a single thymidine-radiographic report available dealing with the time of origin of neurons of a cranial nerve ganglion in a mammal; this is the recent study by Forbes and Welt (1981) of neurogenesis in the trigeminal ganglion of the rat. In the present study we determined the birth dates of neurons of the trigeminal, facial, vestibular, "glosso pharyngeal, and vagal ganglia of the rat. We utilized the progressively delayed com prehensive labeling procedure, a method which, in contrast to the single-pulse labeling procedure, allows the exact quantification of the proportion of neurons formed on a particular day."