Quarterly Journal of Microscopical Science, Vol s2-87, 61-90, Copyright © 1946 by Company of Biologists

Memoirs: Development of Olfactory Organ in Rana nigromaculata

¹ Department of Biology, the National University of Yunnan, Kunming, Yunnan, China

1. The anlage of the olfactory placode arises from the sensory layer of the ectoderm.

2. There is no oro-nasal groove between the olfactory placode and stomodaeum.

3. The primitive choana opens into the endodermal part of the oral cavity.

4. The lateral appendix is the earliest formed blind sac. It degenerates and disappears at the end of the third stage.

5. There are three blind sacs in the larval stage: the upper, anterior lower, and posterior lower sac. The first and third sacs together become the cavum principale and recessus lateralis, while the second becomes the cayum inferius and recessus medialis in the adult stage.

6. The nasal cavities undergo considerable shrinkage during metamorphosis.

7. Extra blind sacs may be formed in the later larval stage.

8. The naso-lacrymal duct arises in the dorso-lateral part of the cavum principale and extends to the lower eyelid. The process of hollowing out appears to begin from the distal end.

9. There are four kinds of glands in the nasal cavity--medial nasal, lateral nasal, Bowman's, and pharyngeal gland. The first one arises earlier than the other three.