The intranuclear deutoplsm and the origin of gametes in the turbellarian Prorhynchus applanatus Kennel

✍ Scribed by E. Ruffin Jones Jr.

• Publisher: John Wiley and Sons
• Year: 1931
• Tongue: English
• Weight: 793 KB
• Volume: 52
• Category: Article
• ISSN: 0362-2525
• DOI: 10.1002/jmor.1050520111

✦ Synopsis

Abstract

It is shown that in Prorhynchus applanatus there exists a type of yolk elaboration which has hitherto not been reported. Formation is within the nucleus through the growth and fusion of nucleoli, but the yolk globule becomes larger than the original nucleolus. The developing individual utilizes the food material contained in the yolk cells in the following order: (1) cytoplasm of the yolk cell, (2) yolk bodies contained in this cytoplasm, (3) intranuclear yolk, (4) nucleoplasm. It is also shown that the germ cells in this form arise from the endoderm by diapedesis, but that the yolk cells are mesenchymal in origin. The sequence of formation of male and female gametes precludes the possibility of the presence of sex hormones such as are found in higher forms.