We investigated the structure of the soft-shelled turtle, Pelodiseus sinensi, spleen and demonstrated that there were several microanatomical peculiarities by light and transmission electron microscopy. In the spleen, the white pulp of the spleen was composed of two compartments, the periarteriolar lymphatic sheath (PALS) and periellipsoidal lymphatic sheath (PELS). No lymph nodules and marginal zones were found. The spleen-blood barrier stood in the PELS and the ellipsoid. The high endothelial lining of penicilliform capillary contained small channels. These channels allowed circulating substances or lymphocytes to enter the ellipsoid. The distal portion of the penicilliform capillaries directly opened to pulp cords. The ellipsoid-associated cell (EAC) was located at the surface of the ellipsoid. Reticular fibers were mainly distributed in ellipsoid and the outer PELS. Both reticular cells and macrophages were distributed in the outer layers of PELS. S-100 protein positive dendritic cells were mainly distributed in out cells layer of the PELS and all over the PALS. Forty minutes after injection, carbon particles of Indian ink were mainly observed in the ellipsoid. Few carbon particles were observed in the outer PELS and fewer carbon particles in the red pulp. These findings suggested that a blood-spleen barrier indeed existed in the soft-turtle, P. sinensi, and it was a complex composed of an ellipsoid (including supporting cells, EAC, and reticular fibers) and the outer compartments of PELS (including dendritic cells, reticular fibers and cells, macrophages).

Chick embryos from stage 14 to stage 31 were studied by means of serial section and light microscopy in order to learn the relationship between the settlement sites of the primordial germ cells (PGCs) and the forming genital ridge. The results showed that: when embryo hatched for 53-56 h, the PGCs reached the coelomic epithelial tissue where gonad would be formed, meanwhile the epithelial tissue began thicker before the PGCs reached. Before stage 19, the final region the PGCs arrived was the thickened portion of the coelomic epithelium, the glycogen in the PGCs cytoplasm maintenance remained unchanged. However at the 3.5-5th hatching day, the glycogen in the PGCs cytoplasm reduced gradually. On the 6th hatching day, the gonad of the embryo appeared the feature of ovary, and the glycogen in the PGCs cytoplasm reduced further. On the 7th hatching day, the differentiation of ovary or testis was obvious and the glycogen in the PGCs cytoplasm later disappeared.

The early embryos are obtained in different time after the former egg had been laid, and the aim of the present study was to observe the development law of chicken early embryo.The embryo development has been divided into the two periods according to morphology of blastodisc. Cleavage period, from 5.5 h (0 h uterine age) to 15.5 h (10-10.5 h uterine age) after the former egg had laid, formation blastodisc of 6-7 layers cell. Later blastocyst period, from 17.5 h (12-12.5 h uterine age) to area pellucida formation after the former egg had been laid. The first division took place at 5 h (0 h uterine age), morular at 11.5 h (6-6.5 h uterine age), and blastocyst at 15.5 h (10-10.5 h uterine age) after the former egg had been laid.

No abstract

The soft‐shelled turtle, Pelodiseus sinensis, and its spleen section showing carbon particles of injected Indian ink mainly in the ellipsoid which composed the blood‐spleen barrier. See Bao et al, on page 1079, in this issue. Anatomical Record 292:1079–1087.