Takasuke Tagawa

Considerations of karyotypic evolution within Vespertilionidae

The karyotypes of each 2 species of Nyctalus and Murina are examined. It is assumed that the diploid number of vespertilionid ancestor was 44 with a fundamental number of 50 and that the mechanism of karyotypic evolution within subfamily Vespertilioninae is mainly caused by centric fusion. On the other hand, the karyotypic alteration of subfamily Murininae may be evolved by non-Robertsonian translocation.

A histochemical study of the innervation of the cerebral blood vessels in the domestic fowl

SummaryAdrenergic and cholinergic nerves innervating the cerebral arteries of the domestic fowl were examined by specific histochemical techniques.The adrenergic nerve plexuses of the cerebral carotid system are markedly denser than those of other vertebrates observed by similar techniques. They form longitudinally elongated meshworks of fine fibres in the vascular wall of the arterial branches. Those innervating the vertebro-basilar system are less dense and more elongated, and, as the size of the artery diminishes, the fibres of the plexus become coarser. In the small pial and parenchymal arteries they are reduced to a few fibres running parallel to, or spiralling around the vascular axis.The cholinergic nerve plexuses are not as dense as the adrenergic system. The acetylcholinesterase activity is very weak, except in the plexuses innervating the cerebral carotid artery and the proximal portion of the anterior and posterior rami. In the vertebro-basilar system, a few thick nerve bundles run alongside the blood vessels of the vertebral and basilar arteries. Cholinergic nerves enter the cranial cavity along the internal carotid, the vertebral and possibly the cerebro-ethmoidal arteries.Intracerebral capillaries and some arterioles are not innervated with cholinergic and adrenergic fibres of peripheral origin, but with ones arising from parenchymal nerve cells.

An ultrastructural study of the cysts in chicken ultimobranchial glands, with special reference to C-cells

SummaryThe ultimobranchial glands of the chicken were examined by electron microscopy and immunocytochemistry using a calcitonin antiserum. Electron microscopy confirmed the presence of C-cells, containing numerous secretory granules storing calcitonin, in the luminal lining of cyst-like structures found in these glands. These cells were furnished with prominent microvillar projections at their luminal surface, and the cytoplasm of the apical region was filled with fibril material. Furthermore, the cells contained prominent junctional complexes and desmosomes at their apico-lateral surfaces. In these C-cells, secretory granules were concentrated near the lumen and some were attached to the apical cell membrane. The luminal content of the cysts had a colloid-like and flocculent appearance, and was frequently seen attached to the cytoplasmic projections or apical cell membrane of the C-cells. Since the cysts progressively increase in volume and number with age, it is suggested that they may partly play a role in the storage of excess or unneeded hormonal products.

The C-banding pattern of 6 Japanese species of vespertilionine bats (Mammalia: Chiroptera)

The C-banding patterns of 6 species of Japanese vespertilionine bats are presented. The variation in amount and distribution of heterochromatin indicates that deletions and additions of heterochromatin have contributed to the karyotypic diversity in Vespertilioninae.

C-banding pattern on the chromosomes of the Japanese house shrew,Suncus murinus riukiuanus, and its implication

The C-band on the chromosomes of the Japanese house shrew,Suncus murinus riukiuanus (Insectivora), was studied. Various types of C-banding pattern were found in the genome of this subspecies. Such banding patterns could be useful for an understanding of autosome and sex-chromosome polymorphisms withinS. murinus.