The ultrastructure of the parathyroid glands of geckos (Gekko japonicus) in the spring and summer season was examined. The parenchyma of the gland consists of chief cells arranged in cords or solid masses. Many chief cells contain numerous mitochondria and free ribosomes, prominent Golgi complexes, abundant granular endoplasmic reticulum and some secretory granules. These features suggest active parathyroid function in the gecko during the spring and summer season.
Large aggregations of glycogen particles are present in the spring and summer season, Myelinlike structures are present in the spring season.

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The ascending pharyngeal artery of the dog was investigated by means of the acryl plastic injection method. This artery usually arose from the external carotid artery, sometimes from the occipital, the posterior auricular, or rarely the ascending palatine of the lingual artery. It ran forwards between the vagus and hypoglossal nerves and continued anteromedially up to the posterolateral wall of the pharynx at the superior margin of the thyropharyngeus muscle, in contact with the inferomedial end of the tympanic bulla. En route it gave rise to the thyropharyngeal, the stylopharyngeal and the styloglossal branches, sometimes additionally the inferior cervical, the digastric and the palatine branches, although all these branches were not observed when it arose from the lingual. It reached to the inferomedial end of the foramen caroticum extemum after giving rise to twigs to the pharyngeal mucosa between the pharyngeal opening of the auditory tube and the pharyngeal isthmus, and the stylopharyngeal, the hypopharyngeal, the levator veli palatine, the thyropharyngeal and the styloglossal branches between the stylopharyngeus and the styloglossus muscles and inferomedial to the tympanic bulla. From this position, the ascending pharyngeal passed above the opening of the auditory tube in about half of all examples observed towards this foramen, but did not intertwine around the loop of the internal carotid. Rarely, it anastomosed with the inferoanterior end of the loop. The main stem of this artery ran forwards between the pterygoid process and the superior wall of the nasopharynx, and gave off small twigs anastomosing with the opposite fellows in the mucosa of the pharyngeal fornix. Finally, it was distributed to the mucosa around the choanae beyond the pterygopalatine suture. In one case, it terminated on the superior margin of the thyropharyngeus muscle, and a branch arising from the loop of the internal carotid divided into the anterior and posterior twigs. The former supplied the mucosa of the nasopharynx, while the latter the levator veli palatini, the thyropharyngeus and the thyroglossus muscles. In conclusion, it can be said that this artery of the dog never contributed to the blood supply of the brain at all, although the ascending pharyngeal of some carnivorae actually constituted a collateral route of the internal carotid, and has probably been presented as a similar vessel in the embryological period of other species.

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The facial artery and its ramifications in the rabbit were studied by the acryl plastic injection method. The facial artery arose independently from the external carotid artery or the maxillary inferomedial to the origin tendon of the digastricus muscle, or in common with the lingual artery. It curved inferomedially lateral to this muscle, but did not curve when its origin was located on the maxillary, where it gave rise to the styloglossal and the digastric branches, then the parotid branch medial to the ventral portion of the gland and the submandibular branch between this gland and the pterygoideus medialis muscle. Both glandular branches in some cases supplied the submandibular lymph nodes and the skin. The artery then passed forwards on the medial surface of the pterygoideus medialis and gave rise to the muscular branches for it and the maxillomandibular branch. The facial artery appeared on the face passing through the vascular notch of the mandible. The submental artery, giving off the infradigastric, the posterodigastric and the mylohyoid branches, curved forwards on the medial surface of the mandible and terminated at the insertion of the digastricus after giving rise to the supradigastric branches. Sometimes it supplied the lymph nodes and the skin covering an area beneath the symphysis and the submandibular region. The primary masseteric branch, giving off twigs to the maxillomandibularis muscle, passed through the vascular notch together with the facial artery and supplied the masseter muscle from its anteroinferior end. The facial passed along the anterior margin of this muscle and gave rise to the inferior labial depressor, the zygomaticoauricular branches and the inferior labial artery. It ascended between the zygomaticus and the buccinator, and finally divided into the superior labial artery and the oral angular branch in the middle of the buccinator, after giving off the secondary and the tertiary masseteric branches and the branch to the masseteric gland. The inferior labial artery passed anterosuperiorly between the buccinator and the zygomaticoauricularis, giving off the branches to the pars molaris of the buccinator and to the superficial mandibular gland and the inferior labial depressor branch up to the angle of the mouth, where it gave rise to the branch to the pars buccalis of the buccinator, the diastema and the gingival branches. It passed medially within the orbicularis oris and formed the inferior labial arterial arch by anastomosing with the opposite fellow. The secondary masseteric supplied the pars molaris and the the masseter from the medial side and the tertiary masseteric from the anterior margin. The branch to the masseteric gland supplied the pars molaris of the buccinator and divided into the anterior and posterior, which supplied the buccal mucosa and gingivae posterior to P₁.

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he ultrastructure of the outer-capsular cell in the bull frog muscle spindle was examined by thin section, freeze-fracture and deep etching electron microscopy. A number of pinocytotic vesicles and microfilament-like materials were observed. Most of the stomata of the vesicles opened to the intra-capsular spaces. This suggests that the chemical composition in the intra-capsular space is controlled at least in part by the capsular cells. A network of microfilament-like materials was especially revealed by deep-etching. Two types of filament,15 and 6 nm in diameter, were found in the superficial network of the capsule. The deep network consisted of filaments with mean diameter of 7.2 nm. These imply that the capsular cells may contribute to mechanical protection of the muscle spindle by the elastic property of their cytoskelton.

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Ultrastructural changes in prolactin cells of the mouse anterior pituitary gland during the estrous cycle were investigated using a morphometric method with the electron microscope. The secretory granules are released by exocytosis and the exocytotic figures showed a large fluctuation in number during the estrous cycle, being adundant in proestrus and estrus, scarce in metestrus and diestrus in a ration of 7.5: 7.5: 1: 2, respectively. The length of the cell perimeter varied in a similar fashion. The volumes of cytoplasm, nucleus and cellorganelles also showed a similar variation throughout the estrous cycle, generally reaching the maximal level in proestrus and/or estrus, being smallest in metestrus and beginning to rise in diestrus. On the other hand, the frequency of exocytotic figures being open to the parenchymal basal lamina which delineated the pericapillary space were three-to five-fold over that of exocytotic figures being open to the intercellular space through every days of the estrous cycle. This suggests that an interaction between the cell membrane and the parenchymal basal lamina may play an important role in the mechanism of exocytosis.

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Retinal projection to the pulvinar area of the Asiatic chipmunk was studied, at both the light and electron microscopic level, using the anterograde transport of horseradish peroxidase (HRP). At the light microscopic level, this approach revealed a narrow strip of labeled retinal terminals in the rostral part of the contralateral pulvinar. This strip of labeling was oriented dorso-ventrally and located in the vicinity of the medial margin of this nucleus. Under the electron microscopic observation, the labeled presynaptic boutons were found to contain ovoid, clear vesicles and make asymmetrical contacts predominantly with the dndrites in the pulvinar region.

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Ovaries were obtained from twelve White Leghorn hens at 154 to 515 days of age, and examined to clarify the histological features of polyovular follicles. It was found that 1)normal follicles containing two or more oocytes were present in the ovaries of hens 154 to 191days old,2) rather large atretic biovular follicles occurred in hens 514 days old, and 3) these polyovular follicles were of separate or contact type, as observed in mammals.

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The present study was undertaken to investigate the entire microcirculation of rat molar pulps using Mercox and colloidal carbon injection methods in conjunction with SEM and LM.
In adult rats the casts of arteries often took a tortuous arrangement in all regions of molar pulps. The artery gave off two same-sized branches in the apical third of the radicular pulp, running parallel to each other. At the junction of the radicular and coronal pulp the arteries diverged into a radial-shaped pattern. The arteries entered coronal area where they divided into two groups, branching either towards the pulp horn or towards the coronal area.
Numerous capillaies were located just below the odontoblastic layer. In the pulp horn a rich capillary network was observed, while in the radicular pulp a diffuse network was seen.
Arteriovenous anastomoses occurred in the center of the coronal area where arterial and venous branches ran parallel to one another.
In immature rats the arteries took a nearly straight course in the radicular pulp.
In the present study tortuous arteries and arteriovenous anastomoses were observed in the pulpal vascular architecture. These tortuous arteries seem to be related to a stagnation of, or decrease in the blood supply. It is suggested that these particular vascular patterns regulate the blood flow throughout the pulp. Also the arteriovenous anastomoses may serve as an effective regulatory system of the pulpal blood circulation.

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