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A study of the internal surfaces of the seminal vesicle, coagulating gland, ampullary gland and ventral prostate of the golden hamster was carried out by scanning electron microscopy. The internal surface of each of these glands was found to display characteristic features in topography and in arrangements of the microvilli. The features are useful in the identification of these glandular tissues in situ.

The infraorbital gland of golden hamsters has been investigated light and electron microscopically. The main results are as follows: (1) The infraorbital gland of golden hamsters is a tubuloacinar gland. Tubuli and acini are enclosed in a basal lamina with some myoepithelial cells. The cells contain secretory granules with a heteromorphic structure. (2) Like salivary glands, the infraorbital gland of the golden hamster has a prominent duct system. Intercalated ducts have a stratified cuboidal epithelium with secretory granules. The intercalated ducts continue into the striated ducts. Cells here show basal striation, which by electron microscopy is resolved as basal invaginations of the plasma membrane with numerous elongated mitochondria in the pockets of cytoplasm so formed. In the epithelium of the striated ducts are many secretory cells. (3) Interlobular ducts consist of a pseudostratified columnar epithelium. The epithelial cells also show basal infoldings of the basal plasmalemma.

An ultrastructural developmental study of hamster vallate taste buds was undertaken to demonstrate the sequential morphodifferentiation of their various cellular components. Under the neurogenic influence of the glossopharyngeal nerve, the undifferentiated epithelial cells of the vallate papilla first acquired fine structure features similar to those seen in the perigemmal adult peripheral cells and the gemmal basal cells. As the development progressed, the relatively undifferentiated basal cells appeared to differentiate into dark and light cell precursors. Mature light cells were frequently noted chronologically before any fully mature dark cells were observed. Transition from light to dark cells, or vice versa, was not noted at any time throughout the investigation, suggesting that light and dark cells originate as separate cell lines from the basal cells of the taste bud proper.

The activity of enzymes hydrolyzing sodium-beta-glycerophosphate, adenosine triphosphate, adenosine monophosphate, and glucose-6-phosphate in the epididymides of adult ram, rabbit, rat and hamster has been investigated histochemically. The enzymes hydrolyzing sodium-beta-glycerophosphate, adenosine triphosphate and adenosine monophosphate were rather similar in their distribution in the intertubular connective tissue of the epididymides of the four species studied. However, the distribution and activity of these enzymes in the stereocilia varied. There was a high activity in the stereocilia of the middle segments of ram, rabbit and rat and in the proximal part of the terminal segment of hamster epididymides. Glucose-6-phosphatase was distributed homogeneously in the epithelial cells of the epididymides throughout the duct. The possible functions of these enzymes in the mammalian epididymis are briefly discussed.

The scleral lamina cribrosa in the eyes of adult rats, hamsters, gerbils and guinea pigs was examined by ordinary histology and by scanning electron microscopy after soft tissue digestion. The complexity of the lamina, when mounted for scanning electron microscopy, was graded on a scale of 0 to 4.5 by three independent observers under X 60 magnification in a stereo microscope. The observers were unaware of the species and were offered the 44 specimens twice in random order. The average variance attributable to an observer was 22 +/- 3% (SE) of the total variance of the gradings. The rat eyes had the least developed lamina cribrosa, with only 1-2 layers of sparse connective tissue. The mean complexity grading of 12 rat eyes was 1.6 +/- 0.15. The lamina cribrosa of the eyes of gerbils and guinea pigs was much more developed with at least 3 layers of abundant connective tissue, the mean grades of complexity being 3.4 +/- 0.09 and 3.5 +/- 0.15, respectively, in 12 eyes of each species. The lamina cribrosa in the hamster eyes was somewhat more developed than that of the rat, but much less than that of the gerbil and guinea pig. The mean grade of complexity was 2.4 +/- 0.14 in 8 eyes. In 6 pairs of rat eyes there was no correlation in grade of laminar complexity between the two eyes of the same animal. The present study makes the rat eye a candidate for experiments where a possible influence of the lamina cribrosa as such is undesired.

The hamster ovarian oocyte surrounded by 2-3 layers of granulosa cells develops a large juxtanuclear complex of organelles, consisting of basophilic substance, mitochondria and some lipid inclusion bodies. The basophilic substance staining for RNA, protein and some diffuse lipoprotein forms the material with which the granular mitochondria, composed of protein and phospholipid, apparently multiply. The lipid inclusion bodies consist of phospholipids. The results of this histochemical investigation have been correlated with those of ultrastructural studies on the hamster oocyte. The paranuclear complex of organelles described in this paper has also been compared and contrasted with that seen in the primordial oocyte of hamster, as reported in the previous publication. The functional significance of juxtanuclear entities has been discussed in relation to the multiplication of organelles to be accumulated during oocyte growth.

A fine-structure study of the hamster fungiform, foliate and vallate taste buds was undertaken for comparative purposes. All three taste bud types shared in common composition of the dark cells, light cells, basal cells, nerve fibers and nerve endings and undifferentiated peripheral cells, but morphological difference existed among them. The foliate and vallate taste buds were quite similar in their ultrastructural morphology. Their dark cells displayed long apical necks, long apical microvilli, apical osmiophilic secretory granules and an abundant rough endoplasmic reticulum. The dark cells of the fungiform taste buds, however, showed no neck formation and lacked apical osmiophilic granules. They had short apical microvilli and relatively scant rough endoplasmic reticulum. There was no difference in the fine structure features of the light cells, basal cells and neural elements of different types of taste buds. Both light and dark cells were much more readily distinguishable in foliate and vallate buds than in fungiform buds at both light-and electron-microscopic levels. Foliate and vallate buds demonstrated homogeneous dense substance within the taste pores while fungiform pores were frequently empty. It is speculated that the differences in taste bud morphology may be due to their different lingual locations and/or may be a reflection of the differences in the inductive influences from different nerves. Furthermore, structural differences may be responsible for varying thresholds to different taste modalities.

The retromolar mucosa of the rat, mouse and golden hamster was observed by light and scanning electron microscopy. Numerous taste bud papillae, each of which formed a low round eminence containing one to several taste buds, were present in the posterior region of the retromolar mucosa, and were especially concentrated in the vicinity of the orifices of the molar glands. This topographical coincidence suggests that the retromolar mucosa of these animals has a functional role as a taste organ. Microridges, arranged in various patterns and small pits, were observed on the surface of the keratinized epithelium of the rat and mouse retromolar mucosa. It appears that the development of numerous microridges is adapted for varied stimuli in the oral cavity.

The adenohypophysis of normal Chinese hamsters of both sexes was examined ultrastructurally. Organs were fixed by intravascular perfusion with S-collidine-buffered glutaraldehyde solution. Seven types of cells were differentiated and, according to morphological characteristics, classified as (1) mammotropes, with very large (400-800 nm) polymorphous secretory granules; (2) somatotropes, either in the storage phase with numerous large, dense granules (average 300 nm), or in the hormone synthesis phase, with abundant endoplasmic reticulum and large Golgi apparatus; (3) corticotropes, with irregular cell shape, and granules (average 160 nm) arranged in lines parallel to the cell membrane; (4) FSH gonadotropes, with abundant and dilated endoplasmic reticulum, and granules (190-320 nm) uniformly distributed in the cytoplasm; (5) LH gonadotropes, with granules (120-220 nm) of varied density; (6) thyrotropes, with irregular cell shape and very small granules (120-160 nm), and (7) agranulated cells. The ultrastructure of the adenohypophysis of the Chinese hamster corresponds closely with observations reported in rats, mice and Syrian hamsters.

Paired cisternae of rough endoplasmic reticulum linked together by two parallel structures exhibiting periodic striations have been observed in the cytoplasm of small pre-antrum oocytes in the golden hamster. They are present only in oocytes from animals older than 3 weeks of age. Two or more such pairs may be associated with one another, and similar structures have been observed in contact with the nuclear envelope. The peak incidence of the paired membranes coincides with a sharp increase in rough endoplasmic reticulum as the oocyte commences rapid growth. A suggested role for the paired membranes in production of new endoplasmic reticulum is discussed.