Charles R. Noback

MORPHOLOGY AND PHYLOGENY OF HAIR

Hair is a structure found exclusively in mammals. With this in mind, Oken named the Mammalia, Trichozoa (hair animals), and Bonnet (1892) named them Piliiera (hair bearers). Of the many aspects of morphology and phylogeny of hair, only four will be discussed. These include (1) the principle of the arrangement of hairs in group patterns, (2) the types of hair and their relation to the principle of the group pattern, (3) a brief analysis of the structural elements of hair and their relation to the types of hair, and (4) the phylogeny of hair, with some remarks on (a) the relation of hair to the epidermal derivatives of other vertebrate classes and (b) aspects of the phylogeny of the hair and wool of sheep to illustrate that marked differences in hair coats exist between closely related animals. Hair is the subject of a voluminous literature. Toldt (1910, 1912, 1914, and 1935), Danforth (192Sa), Pinkus (1927), Pax and Arndt (1929-1938), Trotter (1932), Lochte (1938), Smith and Glaister (1939), and Stoves (1943a) discuss the problem of mammalian hair in general. Wildman (1940), von Bergen and Krause (1942), and the American Society for Testing Materials (1948) discuss the problem of fiber identification as applied to textiles.

ENCEPHALIZATION AND THE LEMNISCAL SYSTEMS DURING PHYLOGENY

Over the past half a billion years the vertebrate nervous system has evolved and through adaptive radiation has developed into the vastly diverse morphologic forms and patterns found in fossil and living species. A phylogenetically oriented concept that attempts to express the evolution of the complex hierarchial organization of the brain into successive levels of centers is called encephalization. This concept is expressed in the brain’s sensory, motor, and behavioral spheres (Noback & Moskowitz, 1962). This presentation will discuss briefly the concept of encephalization and several related topics including: ( 1 ) the lemniscal systems, (2) the axon in the evolution of a lemnicus and other tracts, and (3 ) parallel evolution within the nervous system.

Micromorphology of the placenta of rats reared on marginal vitamin-A-deficient diet

This study describes some effects of marginal vitamin A deficiency on the light-microscopic morphology of the placentas of rats. The placentas obtained were from rat dams reared on a basal vitamin-A-d

STRUCTURAL AND FUNCTIONAL CORRELATES OF “ENCEPHALIZATION” IN THE PRIMATE BRAIN

Encephalization is an inclusive concept expressing the evolutionary specialization of the brain during vertebrate phylogeny. This concept is defined as the evolutionary process whereby the higher centers increasingly dominate the functional activities of the lower centers. Neural activity is influenced to a greater degree by the forebrain (telencephalization) in the higher Primates than in the lower Primates. The expression of encephalization can be grouped conveniently into three spheres: ( 1) sensory spheres; ( 2 ) motor sphere; ( 3 ) behavioral sphere. Sensory sphere. Such general somatic senses as crude touch and pain are distinguished chiefly as a matter of degree rather than of kind. These modalities probably are brought to consciousness in the thalamus of the diencephalon ( diencephalization ) and accordingly are considered to be “thalamic senses” in all Primates (Mehler, 1957; Mehler, Feferman, and Nauta, 1960). The appreciation of the more refined general senses-weight, form, shape and texture-requires the integrative activity of the cerebral cortex. The loss of weight discrimination, induced by the ablation of the postcentral cortex, is greatest in man, less in the chimpanzee, and least in the monkey (Ruch, Fulton, and German, 1938). Thus, a sequence in degree of encephalization with respect to this modality is indicated in these three species. With regard to vision, ablation of the visual cortex demonstrates varying degrees of encephalization in Primates. In man and chimpanzee, total blindness results, but in the monkey, perception of light is retained while that of form and pattern is lost (Marquis, 1935; Kliiver, 1941). Thus, in the evolution of Primates conscious “awareness” of vision and the more discriminative general senses has been corticalized while that of the cruder senses has not. lMotor sphere. Ablation of the motor cortex (precentral gyrus) is followed by less severe motor deficits in lemurs and New World monkeys than in such Old World monkeys as mangabeys and macaques. Greater deficits than these are exhibited by the chimpanzee (Walker and Fulton, 1930; Ruch and Fulton, 1960 ). Sectioning the pyramids of the medulla

The Visual System of Primates in Phylogenetic Studies

A well-developed visual sense coupled with different degrees of manual and digital dexterity are two dominant expressions which characterize the order Primates. Thus, an understanding of the neurobiology of the optic and motor systems of the members of this order of mammals can shed light on several problems of phylogenetic significance.

Phylogenetic and Ontogenetic Aspects of the Lemniscal Systems and the Pyramidal System

A more comprehensive understanding of encephalization during vertebrate evolution would be uniquely attained if one could compare the actual brains of the ancient common ancestors with those representing a sufficiently complete series of subsequent phyletic stages. Unfortunately, such a panoramic view can never be attained since the former and many of the latter brains are lost in the geological past. Therefore, at present, one can trace the process of the phylogenetic development of the brain only through the evaluation and reconstruction of paleoneurological and comparative neoneurological evidence. The phylogenetic interpretations presented below are made with the full awareness of the pitfalls inherent in evaluating data obtained from living descendents. Often only inferences can be made as to whether apparently similar structures found in modern forms are homologous, or are the products of convergent evolution.

Neurobiological Aspects in the Phylogenetic Acquisition of Speech

The ability to articulate words and to communicate verbally is a major hallmark unique to man compared with the living primates from whose ancestors man evolved. Even this dichotomy may not be absolute. Recent evidence demonstrates that vervet monkeys in Kenya, East Africa, use semantic communication in their alarm calls (Seyfarth et al., 1980). These monkeys use three different alarm calls for three different predators and respond differently and appropriately according to whether the call (live or tape-recorded) means a leopard, a martial eagle, or a python. To a leopard alarm the monkeys run into the trees, to an eagle alarm the monkeys look up, and to a snake alarm the monkeys look down.

Digital epiphyseal fusion in adolescence: A longitudinal study

Distal epiphyseal fusion of the adolescent hand was studied by frequent serial roentgenograms. A unit scoring method for quantitating epiphyseal maturation allowed direct comparison between children without regard to age, sex, or pateern of maturation. The average time for fusion of fifteen digital epiphyses of the hand was approximately 16 months, with a range of from 4 to 28 months. The rate of digital epiphyseal fusion is not correlated with sex, digital length, chronological age, or the number of epiphyses undergoing maturation. Apparently, the total time for fusion of all epiphyses is related to the time required to complete the fusion process in any given epiphysis.