Hisayoshi Nishiyama

The passage of spermatozoa through the vitelline membrane in the domestic fowl, Gallus gallus

SummaryThe developing outer layer of the vitelline membrane of the ovum in the posterior part of the infundibulum of the domestic fowl contains many spermatozoa in nearly parallel orientation with its inner layer. When the acrosomal region of a spermatozoon approaches or contacts the inner layer, promptly undergoes the acrosome reaction. The outer acrosomal membrane and overlying plasma membrane fuse together and the apical region of the acrosome opens, so that the acrosomal contents are released. Meanwhile the spermatozoon remains a time in contact with the surface of the inner layer, and the network of the inner layer just under the tip of the sperm head begins to be dissolved. This dissolution extends downward forming a tunnel, approximately 9 μm in diameter. The spermatozoon then passes through the inner layer obliquely via the central region of the tunnel and arrives at the perivitelline space.

Penetration of spermatozoon into the ovum and transformation of the sperm nucleus into the male pronucleus in the domestic fowl, Gallus gallus

SummaryThe apex of the sperm head which has undergone the acrosome reaction comes in contact with the plasma membrane of the ovum. After the entire surface of the inner acrosomal membrane has come into close contact with the plasma membrane of the ovum, the two membranes fuse to form a continuous membrane. All parts of the spermatozoon that are devoid of plasma membrane penetrate into the ooplasm. As the head of the spermatozoon moves deeper into the ooplasm, the chromatin begins to disperse, and the head of spermatozoon is transformed into a large spherical nucleus with low electron density. At a later stage of the transformation, many small vesicles appear around the nucleus and subsequently fuse to form two continuous membranes. These membranes represent the male pronuclear envelope. The condensation of the chromatin occurs in places in the nucleus, so that the male pronucleus is formed. During the course of the formation of the male pronucleus, the subacrosomal rod and tail become detached from the head and disintegrate.

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl, Gallus gallus

SummaryThe differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.

Fate of spermatozoa that do not participate in fertilization in the domestic fowl

SummaryThe fate of spermatozoa that do not participate in fertilization was investigated by electron microscopy. After artificial insemination, we observed several spermatozoa between the fibers of the outer layer of the vitelline membrane of the ovum. One or more spermatozoa were also found in a phagocytic vesicle of macrophages located in the intercellular space of the mucosal epithelium of the infundibulum or in the outer layer of the vitelline membrane.From these observations, we assume that the superfluous spermatozoa in the lumen of the anterior part of the oviduct might be removed by inclusion into the outer layer of the vitelline membrane and by phagocytosis by macrophages.

Disintegration of spermatozoa in the infundibular sperm-host glands of the fowl

SummaryThe disintegration of spermatozoa in the infundibular sperm-host glands of the fowl was investigated by electron microscopy. After the 15th day following artificial insemination, secretory granules in the epithelial cells of the sperm-host glands increase in number and size, and subsequently the contents of the granules are released into the glandular lumen, so that the electron density of the lumen increases. At this stage, spermatozoa stored in the glands begin to undergo degenerative changes starting from the head. The heads become distended and chromatin of the nucleus begins to disperse as small masses, simultaneously with the destruction of the acrosome. As the dispersion of chromatin progresses, mitochondria of the middle piece become distended and irregular in shape, and then disintegrate. At the last stage, most of the organelles have disappeared, but the fibrous sheath and axial-filament complex are still identified.

Colour exposure of incubating eggs and colour preference of chicks

Abstract Chicks hatched from eggs incubated in the dark showed a strong tendency to choose red rather than green. Among chicks hatched from the eggs exposed to red illumination throughout the incubation there was a slight increase in the number of red-preferring chicks while in the case of those hatched from eggs exposed to green illumination there was a shift of colour preference from red to green. When the chick embryos were exposed to green light at different stages of development, influence of the light on the shift from red to green preference was observed in the chicks hatched from eggs illuminated after 18 days of incubation.

Phagocytosis of spermatozoa by the ovum of the domestic fowl, Gallus gallus at the time of fertilization.

SummarySpermatozoa with intact acrosomes, as well as those coming into contact with the ovum at a smaller angle, and morphologically abnormal spermatozoa reach the plasma membrane of the ovum via an extensively dissolved zone of the inner layer of the vitelline membrane. This zone is assumed to be formed by overlapping of two or more tunnels formed by spermatozoa that had previously come into contact with the ovum.When a spermatozoon comes into contact with the plasma membrane of the ovum, many cytoplasmic processes extend outwards and cover it. Thereafter, the plasma membranes of the processes fuse, thereby phagocytizing the spermatozoon. It is assumed that the phagocytized spermatozoa cannot undergo transformation into male pronuclei and that they degenerate soon after phagocytosis.

Diurnal Rhythm of Pituitary Gonadotropic Activity of Male Japanese Quail in Relation to Testicular Growth

雄ウズラを1日齢から28日齢まで14時間(5:00-19:00)照明10時間暗黒(14L:10D)下で,29日齢から49日齢までは8L(5:00-13:00):16D下で飼育し,その後再び14L:10D下に移し,長日刺激を行なった.照明を8L:16Dから14L:10Dに変えた場合,精巣の重量はその2日目までは変化しなかったが,その後35日目まで増加した.特に7日目から21日目までの間には急激な重量増加がみられた.35日目以降においてはその重量はプラトーに達した.鶏雛精巣32P取込法によって測定した下垂体前葉の性腺刺激ホルモン(GTH)力価は8L:16D下および14L:10D処理1日目において内変動を示さなかったが,処理2日目には照明開始14時間後の19時に1つのピークを示した.14L:10D処理7日目と21日目においては照明開始3時間後の8時と照明開始17時間後(暗黒開始3時間後)の22時に2つのピークが認められた.また14L:10D処理35日目と49日目においては照明開始14時間後の19時のみにピークが見出された.これらの事実から,雄ウズラの下垂体前葉のGTH力価は照明を短日から長日に変えた場合に日内変動を示すようになり,その変動のパターンは精巣の発達と関連して変わるものと考えられる.

Changes of Blood Glucose Level before, during and after Oviposition in the Domestic Fowl

In mammals, neurohypophysial hormones influence the contractility of certain smooth muscles and play a physiological role in the regulation of the metabolism of water. They may also produce hyperglycemia1,2), though the physiological significance of this response has not been known yet. A hyperglycemic effect has been shown when arginine vasotocin was injected into lampreys and toads3,4) and when oxytocin or vasotocin was given intravenously to chicken5,6). It has not been known, however, whether endogenous neurohypophysial hormones, which would be released at oviposition in the laying hen, show a hyperglycemic effect like oxytocic substances have. The present experiment was undertaken to investigate the change of blood glucose level before, during and after oviposition in the laying hen. The blood glucose level of the hen administered with oxytocin was also determined.