File:Caldwell06.jpg

PLATE 31. Four sections through the germinal disc of Echidna and Ornithorhynchus

Four sections through the germinal disc of Echidna and Ornithorhynchus. The violet corresponds to the distribution of the more active protoplasm. The yellow yolk spheres are coloured buff.

Fig. 1. Echidna. - Median section through the germinal disc of an unsegmented ovum taken from the lower part of the Fallopian tube, measuring 3.2 mm. in diameter : sh, shell ; alb, albumen ; vm, vitelline membrane.

Fig. 2. Echidna. - Stage of four segmentation nuclei. Lateral section through one pah-of nuclei made in a plane at right angles to the first furrow ; ovum 4.5 mm. in diameter : n₁ nucleus of smaller area ; n₂ , nucleus of larger area. Other letters as in fig. 1 .

Fig. 3. Oraithorhynchus. - From open end of Fallopian tube, 2.6 mm. diameter. Stage of eight segmentation nuclei : ch, pro-albumen.

Fig. 4. Echidna. - From uterus, 5 mm. in diameter. Median vertical longitudinal section through germinal disc : mn, coagulum ; ep, epiblast ; hi/, hypoblast. Other letters as in fig. 1.

Zeiss, oc. 2, obj. c. : cam. luc.

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Links: plate 31 bw | plate 31

Reference

Caldwell WH. The Embryology of Monotremata and Marsupialia Part I. (1887) Phil. Trans. Roy. Soc 178 B.

Cite this page: Hill, M.A. (2024, April 24) Embryology Caldwell06.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Caldwell06.jpg

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