tra2^B/tra2^ts1 transheterozygotes shifted from 18[o]C into 29[o]C upon reaching adulthood do not show significant mitotic index differences in female and male adult posterior midguts, as compared to controls.

XX tra2^ts1 animals reared at the permissive temperature until the early prepupal stage and then shifted to the restrictive temperature for metamorphic development often have hybrid male-female reproductive organs. In these animals, the male ejaculatory duct and female oviduct are typically present as separate organs. However, the female spermathecae and uterus and male ejaculatory bulb are typically absent, and in their place male/female hybrid organs are found connected to the ejaculatory duct and oviduct anteriorly and to the external genitalia posteriorly. XX tra2^ts1 animals raised at the permissive temperature until the late prepupal stage and then shifted to the restrictive temperature develop pseudomale reproductive organs.

Homozygous clones in the repressed male primordium of female genital discs show overgrowth. Homozygous and sister wild-type clones in the growing female genital primordium are similar in size. Homozygous XX larvae develop into female adults if reared at 18^oC and develop into male adults if reared at 29^oC. When homozygous XX larvae are raised at 29^oC and then given a pulse at 18^oC (female-determining temperature) for 48 hours at any time from between 1-2 to 4-5 days after egg laying, the male genital disc develops normal male adult genital structures and not female ones. This occurs even if the 18^oC pulse is applied during pupation. When homozygous XX larvae are raised at 18^oC and then given a pulse at 29^oC (male-determining temperature) for 24 hours before the end of the first larval stage, they produce female and not male genital structures. However, later pulses of 29^oC give rise to male genital structures (and reduce female genital structures), except when close to pupation. The male genital structures are never complete and the penis apparatus and hypandrium are very reduced in size compared with wild-type males. In some cases it is possible to observe small pieces of ventral female analia. The capacity of the female genital disc to differentiate adult genital structures is reduced when the temperature pulse is applied during metamorphosis. When homozygous XX larvae are raised at 18^oC and then given a pulse at 29^oC (male-determining temperature) for 24 hours, overgrowth of the repressed male primordium is seen in the genital disc when the temperature pulse is given after the end of the first larval instar stage.

The developmental capacity of the female genital primordium to develop adult structures is greatly reduced when XX ; tra2^ts1/tra2^ts1 larvae are shifted to 29^oC 0 to 12 hours before puparium formation. The dorsal vaginal plate is present. Hypandrium and penis structures are formed which are enclosed by the remaining vagina or by cuticle whose type is difficult to identify, forming a "secondary penis". No adult female genital structures are formed when XX ; tra2^ts1/tra2^ts1 larvae are shifted to 29^oC 12 to 24 hours before puparium formation, instead a "secondary penis" resembling a complete penis apparatus is formed, although it is somewhat smaller than the penis apparatus of a wild-type male. Some of these flies have two complete penis apparatuses. The earlier in the development of XX ; tra2^ts1/tra2^ts1 larvae that the shift to 29^oC is carried out, the more types of males genital structures, with greater differentiation, are formed. The structures formed follow a sequence, with the genital arch and lateral plates being the first structures to differentiate, followed by the clasper, hypandrium and penis apparatus. The genital disc of XX ; tra2^ts1/tra2^ts1 larvae shifted from 29^oC to 16^oC loses the ability to differentiate male genital structures and becomes able to differentiate female genital structures. Fewer types of male structures, and more types of female structures are formed the earlier in larval development the shift from 29^oC to 16^oC is carried out. Temperature shifts from 16^oC to 28^oC in XX ; tra2^ts1/tra2^ts1 larvae result in the quick formation of pure male anal plates, while in shifts from 29^oC to 16^oC the formation of pure female anal plates occurs gradually.

Temperature shift experiments between male and female specifying temperatures at various times during larval development demonstrated that abdominal neuroblasts adopt a male or female state at the end of the first larval instar.

Male specific muscles were found in female flies bearing any combination of tra2^ts1 or tra2^ts2 alleles reared at the female specifying temperature, 16^oC, or the male specifying temperature, 29^oC.

XX homozygotes raised at the restrictive temperature (29^oC) until the late third instar larval stage, and then shifted to the permissive temperature (16^oC) have male somatic reproductive organs. XX homozygotes raised at an intermediate temperature (25^oC) throughout development are intersex, having both male and female internal reproductive organs.

XX flies are nearly normal but sterile females at 16^oC, intersex at 18^oC, and pseudomales at 29^oC.

Homozygous XX flies shifted to the restrictive temperature immediately after eclosion produce yolk proteins. Mature eggs are present in the ovaries after 2 days, but the eggs are not laid. After 6 days some early egg chambers show signs of degradation. XX tra2^ts1/tra2^ts2 flies shifted to the restrictive temperature immediately after eclosion also have degenerating egg chambers after 10 days at 29^oC. Homozygous XX tra2^ts1 or XX tra2^ts1/tra2^ts2 ovaries transplanted into male hosts and kept at the restrictive temperature can mature and become vitellogenic.

tra2^Pd2/tra2 females pseudomales. temperature-sensitive