Complex sentence: The research group further through their graph plot, examined that the growth of testes was not uniform with proportional growth initially which soon flattened to increase with different slopes and spikes consistently throughout the whole length of the gestational period.
Split into simpler sentences: The research group through their graph plot studies further examined that the growth of testes was not uniform with proportional growth at the initial stages. It soon flattened to increase with different spikes consistently throughout the whole length of the gestational period.