Fig 2. Females are more susceptible to immunological pressure than males in rhesus macaques.

The body lengths of females (A) and males (B) from rhesus macaques, were shorter than their equivalents from rabbits, but the two male populations overlapped considerably (B) whilst the females did not (A). The detailed difference in females from the two hosts, a mature female from a rabbit (C) and three from rhesus macaques (D to F) all to scale (bar = 1mm), are compared. (C) The rabbit worm has black hemozoin pigment present along the whole length of the body. Females from monkeys were smaller and showed different levels of pigment in the gut: (D), Black group were full of pigment from ovary to tail, plus traces in the anterior; (E), Intermediate group had incomplete pigment only in the posterior region; (F), White group had virtually no pigment anywhere.