Melvin Grumbach, a clinician and researcher who described the hormonal dynamics of puberty and numerous endocrine disorders, has passed away at age 90.

The flatworm, Macrostomum hystrix, can inject its own sperm into its head, a new study shows.

Scientists report for the first time that a snail’s seminal fluid proteins can suppress the mating success of the male side of its hermaphroditic partner.

A female bulldog with testicles but no SRY gene considered scientific anomaly.