|Diformismo sessula a livello embrionale in Penilia avirostris Dana = Sexual dimorphism at the embryo stage in Penilia avirostis Dana|
Gaino, E. (1971). Diformismo sessula a livello embrionale in Penilia avirostris Dana = Sexual dimorphism at the embryo stage in Penilia avirostis Dana. Cah. Biol. Mar. 12(3): 283-289
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
The investigation was carried out with 211 embryos of P. avirostris obtained from a plankton sample collected in the Atlantic water at Sandy Hook, USA, in the autumn of 1962 The embryos were at substage 12 (the last of 12 substages established by Della Croce and Kettanin, 1965) when the postabdomen is evident and the prenatal development completed. The morphological study was carried out with individuals in toto and enlargements up to 1000 chi were used in the microscopic examinations. Results showed that it is possible to distinguish male from female individuals at the embryo stage on the basis of differential characters (described). The copulatory organs were well visible in the males at substage 12. In some specimens it was possible to recognize the male embryos even at substage 11. It is stated that even if one individual of P. Avirostris undergoes a change soon after birth, this change brings an increase in size and not differentiation, as organogenesis is completed before birth.