Police Scotland is reiterating its appeal for information relating to the disappearance of Christine 'Renee' MacRae and her three-year-old son Andrew who have not been seen since November 12, 1976.
Andrew was born on October 9, 1973 - meaning that he would have turned 45-years-old today.
Andrew's pram which is believed to have been with them when they went missing has also never been recovered.
The pram is described as being a Silver Cross Carnival collapsible, chrome plated frame with a blue canvas cover.
Officers are keen people cast their minds back and think about whether they saw a pram such as this around the time of Renee and Andrew's disappearance or since.
The investigation into the disappearance of Andrew and his mother has been ongoing since their BMW car was discovered near Dalmagarry south of Inverness.
Officers from Police Scotland's Major Investigations Team and Marine Investigation Unit recently spent several days at Leanach Quarry near Culloden as part of these ongoing enquiries.
This was part of the ongoing investigation into the disappearance of Renee and Andrew, during which officers have been revisiting key areas of interest in order to establish if there are any further opportunity to progress enquiries.
Police Scotland also constantly review advances in forensic science and review existing evidence in order to identify any new available investigative opportunities which may have arisen over the years.
Detective Inspector Brian Geddes said: "At the heart of this case is a family who are quite rightly seeking closure.
"They have lost a young mother and her son who have not been seen for more than four decades.
"Andrew was just a young child when he disappeared with his mother and today would have turned 45-years-old.
"Investigations such as this do not end until we can offer answers to the family of Renee and Andrew and we maintain close ties with them.
"The passage of time is no barrier and we continue to urge anyone who can help us provide closure to the family to come forward, either by calling Police Scotland on 101 or anonymously to Crimestoppers on 0800 555 111."